1. Field
This disclosure relates to increasing fluidity of a flowing fluid.
2. Description of the Related Art
Fluidity is a measure of the resistance of a fluid which is being deformed by either shear stress or extensional stress. In everyday terms (and for liquids only), fluidity is “pourability”. Thus, water is usually considered “thin”, having a higher fluidity, whereas pitch is “thick” having a fluidity about 100 billion times lower than water. Fluidity describes a fluid's internal resistance to flow and may be thought of as a measure of fluid friction. For example, low-fluidity lava will create a tall, steep stratovolcano, because it cannot flow far before it cools, while high-fluidity lava will create a wide, shallow-sloped shield volcano. All real fluids (except superfluids) have some resistance to stress.
Fluidity in gases arises principally from the molecular diffusion that transports momentum between layers of flow. The kinetic theory of gases allows accurate prediction of the behavior of gaseous fluidity. In general, fluidity of a gas is independent of pressure and varies inversely with temperature.
In liquids, the additional forces between molecules become important. This leads to an additional contribution to the shear stress. In general, fluidity of a liquid is independent of pressure (except at very high pressure), and tends to vary directly with temperature. The dynamic fluidities of liquids are typically several orders of magnitude lower than the dynamic fluidities of gases.
Fluidity of fluids is important in many areas of science, engineering, industry and medicine. In many cases it is desirable to increase fluidity. For example, increasing fluidity of crude oil is important to transporting offshore oil via undersea pipelines. Increasing the fluidity of gasoline or diesel can improve the fuel atomization, which can lead to more efficient combustion and less pollution. Increasing blood fluidity can improve circulation and prevent cardiovascular events.
For liquid suspensions such as crude oil, it has been shown that the fluidity can be increased through exposure to a specific field, having a specific type, power and duration. It is believed that the specific field causes particles in the crude oil to aggregate, and therefore increase the volume fraction available to the suspended particles.
For liquid mixtures such as diesel fuel, there has been some theorization that the fluidity can be increased through exposure to a field. According to these theories, an applied field effects a liquid mixture similarly to a liquid suspension, causing larger molecules in the liquid mixture to aggregate, and therefore increasing the volume fraction available to the molecules.
Generally, the effective fluidity of a liquid suspension depends on how much freedom the suspended particles have in the suspension. Lower fluidity translates into less freedom for the suspended particles, and higher fluidity translates into more freedom for the suspended particles. Theory predicts that by aggregating small particles into larger ones in a liquid suspension, the effective fluidity will increase even though the volume fraction of the particles remains the same.
According to one theory, if the applied field is strong enough to overcome Brownian motion, the particles aggregate and align in the field direction. If the field interaction is too strong, though, the particles can quickly aggregate into macroscopic chains or columns and jam the liquid flow, decreasing fluidity. If the field interaction is too weak, though, the clumps are too small to increase effective fluidity.
Some experiments found that the fluidity increases can remain even after the field is no longer present. However, over time the fluidity increase faded as the aggregated particles dissemble under Brownian motion. Experiments on crude oil found that the fluidity increase faded after about two hours at room temperature.
Throughout this description, elements appearing in figures are assigned three-digit reference designators, where the most significant digit is the figure number and the two least significant digits are specific to the element. An element that is not described in conjunction with a figure may be presumed to have the same characteristics and function as a previously-described element having a reference designator with the same least significant digits.